Soil nutrient status and crop productivity after 6 years of conservation tillage in a subtropical dryland

Conservation tillage is considered one of the most indispensable management practices for crop productivity and soil health in rainfed areas world over. The present study aimed to assess performance of conservation tillage in contrast with conventional tillage for different crop sequences on soil quality and yield productivity under the subtropical dryland conditions of Pothwar, Pakistan. Present study was carried out in the plots of an existing long-term field trial initiated in 2011 where four tillage systems viz. conventional tillage (CT, moldboard), minimum tillage (MT), reduced tillage (RT), and zero tillage (ZT) were compared. In 2015, for current study, each tillage plot was divided into three subplots for crop sequences viz. fallow-wheat (Triticum aestivum) (F-W), mungbean green manure (Vigna radiata)-wheat (M-W), and sorghum fodder (Sorghum bicolor)-wheat (S-W). Soil fertility in terms of NO3-N, P, and K was significantly enhanced by long-term application of RT and ZT tillage systems. Among crop sequences, F-W and M-W had higher soil fertility than S-W sequence. Biomass yield of summer crops was the highest under RT tillage that was 37.31 t ha−1 and 42.01 t ha−1 for sorghum and 19.49 t ha−1 and 26.47 t ha−1 for mungbean in 2015 and 2016, respectively. The lowest biomass of both crops was produced by ZT, mainly due to poor germination and lesser plant height. Grain yield of winter wheat was also statistically highest under RT tillage especially in F-W and M-W sequences. Wheat yields were 2.89 t ha−1 and 2.84 t ha−1 in 2016 and 2.63 t ha−1 and 2.61 t ha−1 in 2017, respectively. Reduced tillage system should be promoted for the improvement of soil fertility and crop productivity in Pothwar and other subtropical dryland areas.